Sampling apparatus



'Sept. 6, 1960 Filed Feb. 4, 1957 R. DESBRANDES 2,951,537

SAMPLING APPARATUS 2 Sheets-Sheet 1 3 5 II A l8 3/ 1A 'I/AZV/l/IJ INVENTOR.

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14/: A froze/r5 y Sept. 6, 1960 R. DESBRANDES 2,951,537

SAMPLING APPARATUS Filed Feb. 4, 1957 2 Sheets-Sheet 2 ma W borehole.

United States Patent O SAlVIPLING APPARATUS Robert Desbrandes, Houston, Tex., assignor, by mesne assignments, to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Feb. 4, 1957, Ser. No. 637,913

11 Claims. (Cl. 166-162) ratus of the type disclosed in Patent No. 2,674,313 to 1 L. S. Chambers and for convenience will be described in this connection.

The fluid sampler disclosed in the patent to Chambers includes a support adapted to be lowered into a borehole drilled into the earth and positioned at a level of a formation of interest. The support carries pack-off and back-up shoes and actuators are provided for driving the shoes into engagement with the sidewall of the Thus, that portion of the formation under the pack-oft" shoe is sealed from the drilling liquid that usually fills the borehole, and fluid from the formation may flow via an entry port in the pack-off shoe to a sample-retaining chamber within the support. After a desired amount of fluid is obtained, the sample-retaining chamber is closed, the shoes are retracted and the apparatus is withdrawn from the borehole so that the sample may be measured and analyzed.

Apparatus of the foregoing type has been used successfully in obtaining samples of earth formation fluids and has performed very satisfactorily in a large number of operations. However, under perfectly normal borehole conditions fluids in a formation of interest very often are a mixture of the connate fluids and the fluid which invades the formation from the drilling mud. Thus, a recovered sample may not be entirely representative of connate fluids, but may be more indicative of this mixture.

It is, therefore, an object of the present invention to provide a new and improved fluid sampler affording more information concerning connate fluids in a body under investigation than heretofore possible.

Another object of the present invention is to provide a new and improved fluid sampler for obtaining a sample in the form of discrete volumes, each characterizing the body under investigation in a particular way.

Yet another object of the present invention is to provide a new and improved fluid sampler in which the sample is separated into two or more discrete volumes in the order of their admission.

A further object of the present invention is to provide a new and improved fluid sampler for use in a borehole containing a drilling mud to obtain a plurality of discrete samples from a selected earth formation wherein the last volume recovered is more representative of the connate fluids than previous volumes which contain more of the invading fluids.

A fluidsampler in accordance with the present invention comprises a body having a fluid-receiving cylinder and provided with a portion adapted to define a sampleadmitting opening to the cylinder, a piston movably positioned in the cylinder and means responsive to a predetermined displacement of the piston for effectively providing another piston movably positioned in the cylinder. The other piston is disposed intermediate the aforesaid portion of the body wherein a sample-admitting opening is defined and the first-mentioned piston whereby discrete fluid samples are maintained on opposite sides of the other piston.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a perspective view of a sidewall fluid sampler in which the present invention may be embodied shown in operative position within a borehole drilled into the earth;

Fig. 2 is a cross-sectional view taken along lines 2-2 of Fig. 1, drawn to an enlarged scale, illustrating in detail apparatus embodying the present invention;

Figs. 3, 4 and 5 are schematic, simplified representations of the apparatus illustrated in Figs. 1 and 2 demonstrating different portions of an operating cycle of the apparatus embodying the present invention; and

Fig. 6 is a schematic, simplified representation of another embodiment of the present invention illustrated in one portion of an operating cycle.

In Fig. 1 of the drawings, apparatus embodying the present invention is shown disposed in a borehole 10 traversing earth formations 11, 12 and 13 and containing a drilling liquid 14 such as a water base or oil base mud. It is assumed that formation 12 is the one of interest from which a fluid sample is to be obtained and the apparatus is positioned in the borehole 10 so that a central section including a normally-retracted pad or pack-off shoe 15 and an oppositely-positioned, normally-retracted back-up shoe 16 are adjacent formation 12.

The apparatus further comprises upper and lower pressure-resistant housing sections 17 and 18 connected together in longitudinally spaced relation by side rails 19 and 20. Hydraulic actuators (not shown) are positioned between the side rails and are employed to drive the shoes 15 and 16 into engagement with respective sidewall portions of the borehole 10. The apparatus thus far described is suspended in the borehole by an electrical cable 21 which, in connection with. a winch (not shown) located at the surface of the earth, is employed to lower and raise the apparatus in the borehole in a customary manner. Conductors of cable 21 are employed for supplying electrical energy from a source 22 at the surface of the earth to various control circuits within the tool 17, 18 and for conveying information from the tool to a recorder 23.

Generally stated, upper housing section 17 contains a hydraulic driver (not shown) of the type described in the above-mentioned patent to Chambers which employs the pressure of the borehole liquid 14 to produce hydraulic pressure for driving the actuators that move the shoes 15 and 16. Housing section 18 contains a samplereceiving chamber to be described in greater detail hereinafter fluidly connected to a central portion 24 of packolf or seal shoe 15. This chamber is provided with a conventional pressure gauge (not shown) where an electrical signal representative of pressure in the chamber is derived and supplied to recorder 23.

Seal shoe 15 is comprised of a central portion 24 which may be in the form of a rigid insert in a resilient sealing face 25. The insertis provided with a front aperture 26 connected to a normally closed bore (not shown). To open this bore, a gun block (not shown) may be pro vided in which a projectile and a propellant are received as disclosed in the patent-to Chambers.

As shown in Fig. 2, housing section 18 is hollow thereby defining a "fluid-receiving cylinder 27 provided with an upper closure 28 and a lower closure 29. A conduit 30 extending through the upper closure 28 is connected by means to be described hereinafter to the bore associated with aperture 26 of insert 24 (Fig. 1). Thus, the carrier of body 18 includes an upper portion adapted to define a sample-admitting opening to cylinder 27.

A first piston 31 is positioned in cylinder 27 and has a peripheral rubber seal 31' and an O-ring 31 effectively sealing the piston to the wall of the cylinder, but permitting the piston to move or slide therein. For the operating condition illustrated in Fig. 2, the piston 31 is in its uppermost position relatively close to upper termination 28;

Intermediate piston 31 and lower closure 29, cylinder 27 is provided with a transverse wall 32 having an aperture 33 forming an orifice through which a cushion liquid 34 normally filling the portion of the cylinder between cylinder 31 and wall 32 may flow. As described in the Chambers patent, the orifice controls the rate of flow of cushion liquid into the portions of the cylinder below the wall 32 thereby to control the speed of movement of piston 31.

Apparatus embodying'the present invention further comprises a second piston 35 positioned in cylinder 27 intermediate upper termination 28 and piston 31. Piston 35 is appropriately sealed to cylinder 27 to prevent the passage of fluid such as by means of peripheral rubber rings 35' and 35" which are arranged to provide a slight amount of friction for a purpose to be described hereinafter, but not to impede appreciably sliding movement of piston 35. This piston has a passage 36 normally providing fluid communication between sections of the cylinder opposite sides of the piston. The lower end of the passage 36 is in the form of an annular, horizontal valve seat 37 and a valve member 38 is movably disposed in a vertical opening 39 in the piston. A compression spring 40 biases the valve member 38 toward the valve seat 37; however, a shear pin 41 extending through corresponding openings in an upper stem portion 42 of the valve member and in the piston 35 prevents movement of the valve member 38 from the position illustrated in Fig. 2. Thus, valve 37, 38 is normally open.

A lower extension 43 of the valve stem is provided with an opening 44 in which at one end a flexible Wire 45 is threaded and fastened. The remaining end of wire 45 is threaded through an opening 46 of a small, upper extension 47 of piston 31 to which it is fastened. The length of wire 45 is chosen to provide a predetermined amount of movement of piston 31 before a downward force is applied to the valve stem portion 43 as will be more apparent from the discussion to follow. For the condition of operation illustrated in Fig. 2, the excess amount or slack in wire 45 is appropriately dressed, such as by providing a number of coils.

To prepare the tool for operation, pistons 31 and 35 are placed at their uppermost positions and a cushion liquid such as water is introduced into the tool to fill the portion of cylinder 27 below piston 31 and above wall 32, as denoted by numeral 34 in Fig. 2. The portion of cylinder 27 below wall 32 is at atmospheric pressure, but because of the relatively small size of orifice 33, the only opening to this portion of the cylinder, the cushion fluid cannot flow. The hydraulic actuating system for the shoes 15 and 16 may then be set so that after the tool is lowered in the borehole to a position such as represented in Fig. l, the actuating mechanism may be energized thereby driving the shoes 15 and 16 toward opposite sidewall portions of the borehole 10.

Thus, as shown in the simplified representation of Fig. 3, where corresponding elements bear like reference numerals, shoes 15 and 16 engage the borehole wall and a seal between the wall and drilling fluid 14 is established by shoe 15. Thereafter, the bore in insert 24 is opened so that a fluid connection with cylinder 27 is completed via aperture 26, a conduit 48, a normally-open valve 49 and conduit 30 in upper termination 28 of the cylinder. Hence, fluids from formation 12 may flow into the upper end of cylinder 27 and since valve 37, 38 is open, such fluids may flow through channel 38 (Fig. 2) and into the space between the pistons 31 and 35. Of course, the rate at which fluid sample is received is determined by movement of piston 31. This depends on the size of orifice 33 which determines the rate at which cushion liquid 34 flows into the lower part of the cylinder below wall 32 as described in detail in the Chambers patent.

It is evident that piston 31 moves downwardly as formation fluids enter the cylinder 27 and when this piston reaches the position illustrated in Fig. 4 the slack in flexible wire 45 is taken up and a downwardly pull is exerted on valve member 38. Since shear pin 41 need only be strong enough to resist the relatively light force exerted by spring 40, and since the frictional forces exerted by sealing elements 35 and 35 of piston 35 on the wall of cylinder 27 are greater than the force required to break pin 41, continued movement of piston 31 causes the pin to shear and spring 40 immediately closes valve 38. Thus, the apparatus embodying the invention comprises means responsive to a predetermined displace ment of piston 31 for effectively closing the passage 36, 37 of piston 35 to fluid communication. As fluid from the formation under investigation continues to flow through inlet 30 it now remains above piston 35; none can go below it. In other words, discrete fluid samples are maintained on opposite sides of piston 35 as it is driven downwardly by the incoming fluid, and by virtue of the fluid entrapped between the pistons, the lower piston 31 continues to move downwardly as the apparatus reaches the operating condition illustrated in Fig. 5. When the piston 31 engages the abutment 32 it stops and fluid ceases to flow into the sample receiving cylinder 27. Accordingly, after a preselected interval of time has passed in which the foregoing function has occurred, valve 49 may be closed to entrap a fluid sample which thus is constituted of a first volume V between the pistons 31 and 35 and a second, discrete volume V above piston 35.

The pads 15 and 16 may then be retracted to the position illustrated in Fig. 1 and the apparatus may be brought to the surface of the earth.

To remove the samples from the tool an appropriate valve system, for example of the type usually referred to as a Christmas tree, is connected to conduit 30 and sample container is positioned at the outlet of the valve system. The valve system. is then opened slightly to atmospheric pressure. The resultant pressure drop in volume V causes the upper piston 35 to move toward upper wall 28 while valve 37, 38 remains closed by spring 40 (Fig. 2). Of course, the biasing force of spring 40 should be selected so that the pressure on valve member 38 to open the valve is greater than the pressure required to move the piston .35. When the upper volume V is drained in its entirety, piston 35 engages upper wall 28 and the resulting pressure difference on the valve member 38 causes it to open against the bias of spring 40 and volume V may be drained.

If desired, a fluid coupling 50 may be provided for the cylinder below wall 32 together with an appropriate valve 51 so that external pressure may be applied to assist in removing the fluid samples. It is evident that where liquids are contained in volumes V and V they may be identified from one another by an increase in pressure at inlet 50 required to extract the lower volume V This is understandable because an additional amount of pressure is required to overcome the bias of spring 40 on valve 37, 38. I

It is thus evident that apparatus embodying the present into easiest invention may be used to obtain useful, additional information concerning the body under investigation. Specifically, a fluid sample from an earth formation under investigation may be separated into two discrete volumes in order of their admission into the apparatus. Accordingly, volume V (the last volume recovered) is more representative of the connate fluids than is the first volume V which would normally contain a greater part of invading fluids.

In constructing one form of apparatus embodying the present invention, some of the design data were as follows:

Friction force of piston 35 lbs 130-150 Effective area of piston 35 sq. in 14.2 Fluid pressure necessary to move piston 35 p.s.i 910 Force exerted by spring 40 when cocked lbs 25 Force necessary to shear pin 41 lbs 75-85 Force necessary to trip valve 38 lbs 50-60 Force to break wire 45 lbs 180-200 Fluid pressure necessary to open valve 38 p.s.i 25

A differential pressure between V, and V of 13l5 p.s.i. will break wire 45. If V contains only liquid, the wire remains intact when the sample in V is recovered. However, if V contains gas, when V is bled oif, the sample expands and wire 45 is broken.

The foregoing data are presented purely by way of example and are not to be construed in any way as limiting the scope of the invention.

It is also within the contemplation of the present invention to provide apparatus arranged to take as many discrete samples as desired. For example, four volumes, V V may be obtained with an arrangement of the type illustrated in Fig. 6. Here as in the arrangement illustrated in Figs. 2-5, cylinder 27 contains a piston 31 connected by a flexible wire 45a to a valve 37a, 38a in a piston 35a positioned above the piston 31. In addition, piston 35a is connected by a flexible wire 45]) to valve 37b, 38b of another piston 35b which, in turn, is connected by a flexible wire 450 to a valve 37c, 380 of still another piston 350.

From the description of the apparatus illustrated in Figs. 3-5, it will be evident that initially the piston-s 31, 35a, 35b, and 350 are positioned in relatively close association at the upper end of cylinder 27 and that the valves in the several pistons are initially open. In operation, on entry of a fluid via conduit 30, piston 31 is displaced downwardly and after the slack of wire 35a is removed, valve 37a, 38a is closed and a sample flows the space above piston 35a. The sequence continues until four discrete volumes are obtained thus pro viding additional information concerning the earth formations under investigation.

Obviously, the lengths of flexible wires 45a, 45b, and 450 determine the relative capacities of volumes V -V They thus may be equal or have any desired ratio to one another.

If desired, separate pressure indications may be derived for each of the volumes V V V and V To this end, pressures recorders maybe mounted to the upper surfaces of each of the pistons 31, 35a, 35b and 350. Of course, the flexible wires 45a, 45b and 450 may be arranged in a known manner to provide insulated conductors for conveying electrical signals. Thus, these pressure gauges may be of the type producing electrical signals representing fluid pressure and by an appropriate flexible electrical connection through the upper end of cylinder 27 and through wall 28 such signals may be conveyed to cable 21 (Fig. l) for transmission to the earths surface.

To assist in identifying the several discrete, sample volumes, appropriate dyes may be used. For example, with reference to Fig. 3, a soluble capsule of one color may be mounted on the upper side of piston 31 and a capsule of another color mounted in a normally closed compartment on the upper side of piston 35. This compartment is suitably arranged to open when valve 37, 38 closes.

Obviously, sampling apparatus embodying the present invention may be utilized in association with other types of devices for completing afluid connection with the formation of interest. For example, tube 48 may be connected to an appropriate portion of a drill stem tester employing one or more annular packers for sealing off a zone in a borehole opposite the formation. Accordingly, a fluid sample in discrete volumes may be obtained.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

-l. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means for defining a sample-admitting opening to said cylinder; a first piston movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sampleadmitting opening and said first piston and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; and means responsive to a predetermined displacement of said first piston for effectively closing said passage of said second piston to fluid communication.

2. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means for defining a sample-admitting opening to said cylinder; a first piston movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sample-admitting opening and said first piston and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; a normally open valve for selectively closing said passage; and means responsive to a predetermined displacement of said first piston for closing said valve.

3. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means for defining a sample-admitting opening to said cylinder; a first piston movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sample-admitting opening and said first piston and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; a normally open valve for selectively closing said passage and including a member movable relative to said second piston thereby to close said valve; and a flexible connection extending between said first piston and said movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sample-admitting opening and said first piston, including means for introducing a given amount of retarding force on movement of said second piston through said cylinder, and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; a valve for selectively closing said passage including a valve seat, a valve member movable toward and away from said valve seat, a spring for urging said member toward said valve seat with a selected force less than the aforesaid given force, and frangible means holding said valve member in a position away from said valve seat but frangible to release said valve member in re sponse to a breaking force less than said retarding force; and a flexible connection extending between said first piston and said valve member and having a selected length so that in response to a predetermined displacement of said first piston a force greater than said breaking force but less than said retarding force is applied to said valve member thereby to permit said spring to close said valve.

5. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means at one end portion defining a sample-admitting opening to said cylinder and an opposite end portion closing said cylinder; a first piston movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sample-admitting opening and said first piston and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; a compartment extending across said cylinder at a section thereor intermediate said opposite ends position and said first piston and having a relatively small fluid passage defining an orifice, said cylinder thereby being adapted to receive a liquid in a section thereof between said first piston and said compartment for controlling the rate of movement of at least one of said pistons; and means responsive to a predetermined displacement of said first piston for effectively closing said passage of said second piston to fluid communication.

6. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means for defining a sample-admitting opening to said cylinder; a piston movably positioned in said cylinder, a plurality of additional pistons movably positioned consecutively in said cylinder intermediate said sample-admitting opening and said first piston and individually having passages pro viding fluid communication between sections of said cylinder on opposite sides thereof; and means responsive to a predetermined displacement of one of said pistons for effectively closing said passage of another of said pistons to fluid communication.

7. A fluid sampler comprising: a carrier having a fluid-receiving cylinder and including means for defining a sample-admitting opening in said cylinder; a first piston movably positioned in said cylinder, second and third pistons movably positioned consecutively said cylinder intermediate said first piston and said sample-admitting opening and individually having passages providing fluid communication between sections of said cylinder on opposite sides thereof; normally open valves for selectively closing respective ones of said passages in said second and third pistons; means responsive to a predetermined displacement of said first piston for closing said valve of said second piston; and means responsive to a predetermined displacement of said second piston for closing said valve of said third piston.

8. A fluid sampler comprising: a carrier having a fluidreceiving cylinder and including means for defining a sample-admitting opening to said cylinder; a first piston movably positioned in said cylinder, a second piston movably positioned in said cylinder intermediate said sample-admitting opening and said first piston and having a passage providing fluid communication between sections of said cylinder on opposite sides of said second piston; valve means for closing said passage of said second piston to fluid communication; and means for actuating said valve means when a predetermined volume or" fluid is contained between said first and second pistons.

9. A fluid sampler comprising: a body having a fluidreceiving cylinder and including means for defining a sample-admitting opening to said cylinder; a first piston movably positioned in said cylinder; a second piston movably positioned in said cylinder intermediate said sampleadmitting opening and said first piston, said second piston and said first piston defining with said cylinder an enclosure having a normally open sample-admitting opening in fluid communication with said sample-admitting opening to said cylinder; and means for closing said sample-admitting opening of said enclosure after it has received a fluid sample whereby discrete fluid samples are maintained on opposite sides of said second piston.

10. A fluid sampler comprising: a body having a fluidreceiving cylinder and including means for defining a sample-admitting opening to said cylinder; a piston first movably positioned in said cylinder; a second piston movably positioned in said cylinder intermediate said sampleadmitting opening and said first piston, said second piston and said'first piston defining with said cylinder a first enclosure having a normally open sample-admitting opening in fluid communication with said sample-admitting opening to said cylinder; means for closing said sampleadmitting opening of said first enclosure after it has received a fluid sample whereby discrete fluid samples are maintained on opposite sides of said second piston; a third piston movably positioned in said cylinder intermediate said sample-admitting opening of said cylinder and said second piston, said third piston and said second piston with said cylinder defining a second enclosure having a normally open sample-admitting opening in fluid communication with said sample-admitting opening to said cylinder; and means for closing said sample-admitting opening of said second enclosure after it has received a fluid sample whereby discrete fluid samples are maintained on opposite sides of said third piston.

11. A fluid sampler comprising: a body having a fluidreceiving cylinder and including means for defining a sample-admitting opening to said cylider; a piston movably positioned in said cylinder and adapted to be displaced therein in response to entry of a fluid sample in said cylinder; another piston movably positioned in said cylinder intermediate said sample-admitting opening and said first-mentioned piston; normally open valve means in said other piston; and means to actuate said valve means to interrupt fluid communication through said cylinder whereby discrete fluid samples are maintained on 0pposite sides of said other piston.

References Cited in the file of this patent UNITED STATES PATENTS 2,147,983 Lindsly -i Feb. 21, 1939 2,364,464 Moore Dec. 5, 1944 2,640,542 Brown et al. June 2, 1953 2,674,313 Chambers Apr, 6, 1954 

